Supplementary Scenario Data

Scenario Methodology

The port cities study determines the number of people that would be exposed to extreme water levels assuming no coastal flood protection measures, which can then be related to the economic assets that would be exposed within the city. Exposure therefore refers to the population and assets that are threatened, taking no account of any defences or other adaptation.

Existing modelling approaches used to estimate flood protection often assume economically optimum standards of protection, and where we do have data, these methods tend to overestimate protection standards in comparison to reality, especially in many poorer countries. The focus of this analysis is exposure rather than ‘residual risk’ (which includes defences and other adaptation). Flood protection is not included explicitly as it is difficult to ascertain accurate and comprehensive data on flood protection in many, if not most, of the cities under study.

A range of climate and other change factors are considered, outlined in the below table. Six main scenarios were investigated to understand changes in exposure given a 100 year return period extreme water level event. Future exposure is evaluated for the 2070s (the decade 2070-2080). The scenarios are outlined in Table 1.